Idle Issue with Clutch Engaged

[BTaylor34]

Have a 2000 TJ 2.5, and wondering if anyone else has had this problem. When coming to a stop, when I push the clutch in, the engine revs up about 400-500 rpm (around 1500), not a lot, but noticeable, and then when I come to a stop it returns to normal, around 800. Engine idles fine, no sputtering or stalling. Oil, Coolant, Temp are fine.

Does this sound like maybe an IAC or TPS going out?

Thanks for the help!

 

[BTaylor34]

Oops, just noticed my error....title should say Clutch Disengaged. (clutch pedal pushed IN) Sorry!

 

[JPNinPA]

Not going out but in need of cleaning. Clean the TB and IAC, check connections and keep the cables clean and lubricated. This is also a sign of a vacuum leak.

 

[oldjpman]

Got an 02 4.0 & I had the same problem. After searching and more searching I found that the half egg shaped washer on the intake bolt at the #6 cylinder had broken. Put a stack of three washers on it, retorqued the bolt end g2g. Hope this helps.

 

[wwch99tj]

Mine does the same thing... revs 1100+ until completely stopped, done it ever since I've owned it 8+ yrs and 160k+ miles.
I've always just thought it was normal?

Sent from my Samsung Galaxy S3 using Jeepz

 

[oldjpman]

I've heard the same thing when I was searching around forms trying to find answers for my problem. I knew it couldn't be normal because motors just don't run that way and mine had just started. Really the only answer I got was that it was definitely a vacuum leak but I had no check engine light and I couldn't hear any hissing noise coming from the motor. I drove the Jeep like that for about 3 months and had not seen any change my fuel economy . The only way I found it was I actually stood over the engine while it was running moving my hand around between the motor in my ear to see if I could hear any noise changes which I had done at least two other times. After doing that for a while I finally heard an alternating sound coming from the #6 injector. That's when I saw the washer missing and man did I feel stupid for missing something like that. One would think you would see evidence of fuel coming out of an area like that but that's not the case. The valve is open only during the downstroke so there's of only suction. As far as check engine light goes to computer doesn't check everything and some vacuum leaks are small enough that the computer cannot pick it up. Post back if you find anything I'd like to know.

 

[oldjpman]

By the way I'm not trying to say it's definitely the intake manifold that's causing your problem. All I'm saying is I believe it's definitely a vacuum leak somewhere. I've had my Jeep since 2003 and in my experience Jeeps are prone to having vacuum leaks.

 

[JPNinPA]

Vacuum leak can be found by spraying carb cleaner or it LWrench slowly around possible leak areas while the engine idles. Listen fit the idle to change when you find the leak.

 

[BTaylor34]

Hey all,
Thanks for the great advice. Cleaned the throttle and sensors, and was still getting a 2000 rpm idle, so used the tb cleaner and sprayed all around as JPN suggested. After going around the hoses with no results, I decided just to spray at random, and she choked up when I hit the intake manifold by the block. After about an hour of so of cooldown time, oldjp hit it on the head! 4 of the bolts on the intake /exhaust manifold were loose enough to wiggle by hand. Tightened em up and cranked her, and purred like a kitten.
Ya'll (<--- yup, southern...lol) really helped out a lot! Thanks again!